Method of detecting and measuring endpoint of polishing processing and its apparatus and method of manufacturing semiconductor device using the same

Abstract

Laser sources output laser lights L.sub.1 and L.sub.2 having different wavelengths so as to increase an accuracy of an endpoint detection of polishing processing by enabling an accurate detection of a film thickness of a layer insulating film on a surface of a wafer to be polished by the CMP processing, the lights are emitted from a detection window via a beam splitter to the layer insulating film formed on the surface of the wafer to be polished by a pad, different optical detectors detect interference lights corresponding to the laser lights L.sub.1 and L.sub.2 reflected and generated from a surface of the layer insulating film and a pattern under the surface via the detection window, the beam splitter, and a dichroic mirror, the detection results are supplied to a film thickness evaluation unit 7, a film thickness of the layer insulation film is detected on the basis of a relationship between intensities of the reflected interference lights to the laser lights L.sub.1 and L.sub.2 or the intensity ratio, and an endpoint of polishing processing is determined when the film thickness is equal to a predetermined value.

Description

BACKGROUND OF THE INVENTION[0001] 1. Field of the Invention[0002] The present invention relates to an endpoint detecting of polishing processing of a semiconductor device, and more particularly to a method of detecting an endpoint in smoothing of a wafer surface and its apparatus, a polishing method with an endpoint detecting function and its apparatus, and a method of manufacturing a semiconductor device using the same.[0003] 2. Related Background Art[0004] A semiconductor device is manufactured by forming a film on a silicon wafer (hereinafter simply referred to as wafer) and forming an element or wiring pattern through an exposure in a desired pattern and an etching process of the exposed portion. Subsequently to forming the element or wiring pattern as described above, a transparent layer insulating film made of SiO.sub.2 or the like is formed to cover the element or wiring pattern and the next element or wiring pattern is formed on the layer insulating film, thus causing the ma...

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Benefits of technology

0016] In other words, in accordance with a first aspect of the present invention, there is provided a method and an apparatus for detecting an endpoint of polishing processing, wherein the film formed on a wafer surface under polishing processing is irradiated with lights having two or more different wavelengths, a white light or an ultraviolet (UV) light, and a film thickness of the film formed on the semiconductor device surface is evaluated based on an intensity of a reflected light or a spectral intensity from the film or an intensity of the UV light, thereby detecting an endpoint of polishing processing for the film. According to these method and apparatus, it is possible to increase an accuracy of detecting the endpoint of polishing processing for the film even for a small polishing processing amount or independently of a film structure.

0017] In a second aspect of the present invention, there is provided a polishing processing method with an endpoint detection function and its apparatus, wherein the film formed on a wafer surface under polishing processing is irradiated with lights having two or more different wavelengths, a white light or an ultraviolet (UV) light, and a film thickness of the film formed on the semiconductor device surface is evaluated based on an intensity of a reflected light or a spectral intensity from the film or an intensity of the UV light, thereby detecting an endpoint of polishing processing for the film to terminate the polishing processing. According to these method and apparatus, it is possible to increase an accuracy of detecting the endpoint of polishing processing for the film even for a small polishing processing amount or independently of a film structure.

0018] In accordance with a third aspect of the present invention, there is provided a method of manufacturing a semiconductor device, wherein means for evaluating the film thickness is incorporated into a polishing processing machine to evaluate a deteriorated condition of a polishing pad, thereby optimizing the polishing processing conditions and dressing conditions of the pad at the polishing processing. With this method, an object to be polished, for example, a film formed on the wafer becomes further smoother, thus enabling a high-precision film thickness control or a high-grade polishing processing control to improve a throughput.

0019] The semiconductor device manufacturing method according to the present invention may be such that the condition is evaluated at a plurality of positions on the wafer surface by pad evaluation means, thereby enabling an evaluation of a film thickness distribution of a wafer and a film on the wafer surface during processing.

0020] In addition the semiconductor device manufacturing method according to the present invention may be such that a CMP process can be stabilized and optimized on the basis of a film evaluation result of the film formed on the wafer surface.

Problems solved by technology

The under element or wiring pattern, however, generates an uneven surface of the layer insulating film provided to form the next layer on the element or wiring pattern layer on the wafer.

The increase of the unevenness on the surface of the layer insulating film makes it hard to achieve a uniform exposure condition over the entire film formed on the layer insulating film, and therefore the layer insulating film is smoothed before forming the film.

If a lot of wafers are polished, however, the pad 1 wears out on its surface, thereby decreasing a polishing performance of the pad 1 or causing a serious condition in which the layer insulating film on the wafer surface has flaws due to contaminants adhering to the surface of the pad 1.

As an important problem in this CMP processing, there is an endpoint detection for terminating polishing when the layer insulating film on the wafer surface has been polished into a predetermined film thickness.

In these methods, however, the detection cannot be precisely controlled due to uneven polishing rates and further the control takes plenty of time.

Therefore, a gradient of the curve P is low and therefore even if a predetermined intensity I is detected, it is hard to detect it accurately.

Accordingly the conventional in-situ measurement is effective for a relatively large processing amount (polishing amount), while it is often incapable of detecting an endpoint accurately in case of a small processing amount or according to a film structure.

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